The Bally Professional Arcade is a full-color videogame system based on the mass-RAM-buffer technique. A mass-RAM-buffer system is one in which one or more bits of RAM are used to define the color and intensity of a pixel on the screen. The picture on the screen is defined by the contents of RAM and can easily be changed by modifying RAM.

The system uses a Z80 microprocessor as its main control unit. The system ROM has software for four games: Gunfight, Checkmate, Scribbling, and Calculator. Additional ROM can be accessed through the cartridge connector. Three custom chips control the video interface, special video processing functions, keyboard and control handle interface, and audio generation.

The system exists in both high-resolution and low-resolution models. The three custom chips can operate in either mode. The mode of operation is determined by bit 0 of output port 8H. It must be set to 0 for low-resolution and 1 for high-resolution. This bit is not set to 0 at power up and must be set by software before any RAM operations can be performed.

NOTE: The Bally Arcade only has access to low-resolution output. High-resolution output was available in certain Bally arcade titles. Further references to the high-resolution mode are omitted throughout the Better Bally Book. For further information about this mode, please consult the original Nutting Manual.

Hardware is divided into the following subsections:

Image source: Bally Alley